1. Field of the Invention
The present invention relates to a method of fabricating an organic light emitting display (OLED) and, more particularly, to a method of fabricating an OLED using a donor substrate having a surface-treated buffer layer.
2. Description of the Related Art
Among flat panel displays (FPDs), an organic light emitting display (OLED) is quite appropriate for a medium that displays moving images irrespective of its sizes because the OLED has a fast response speed of 1 millisecond or less and a wide viewing angle, consumes low power, and is an emissive display. Also, the OLED can be fabricated at low temperature and in a simple process based on a conventional semiconductor manufacturing technology. For these reasons, the OLED has attracted much attention as the next-generation flat panel display (FPD).
The OLED can largely be classified into a polymer type using a wet process and a small-molecule type using a deposition process, according to the types of material and process used for an organic light emitting device. If an emission layer (EML) is formed of a small-molecule material, it is deposited in vacuum using a shadow mask. If the EML is formed of a polymer material, it is formed by an inkjet printing method. However, it is difficult to perform the vacuum deposition process using the shadow mask on a large-sized substrate. Also, since the inkjet printing method is a wet process, an underlying layer should be formed of only limited kinds of materials, and a bank structure should definitely be formed on a substrate.
As a substitute for the above-described methods of patterning the EML, a laser-induced thermal imaging (LITI) process has recently been developed.
During the LITI process, a pattern is formed by transferring a pattern forming material to a target substrate using laser beams irradiated from a light source. Such an LITI process requires a donor substrate on which a transfer layer is formed, a light source, and an acceptor substrate.
The donor substrate includes a base substrate, a light-to-heat conversion layer, and a transfer layer. During a transfer process using the donor substrate, laser beams are irradiated on a predetermined region of the base substrate and then converted into heat by the light-to-heat conversion layer. The heat transforms adhesion properties between the transfer layer and the light-to-heat conversion layer so that the transfer layer is transferred to the acceptor substrate.
Accordingly, the performance of the donor substrate depends on adhesion properties between the donor substrate and the transfer layer, and a poor adhesion between the transfer layer and the light-to-heat conversion layer may cause failures during the process of transferring the transfer layer to the acceptor substrate.